Rainwear often gets overlooked as a key component in a comprehensive flame-resistant clothing program. When part of an FR clothing program, the general rules for outerwear also apply to rainwear: Never wear non-FR rainwear over flame-resistant uniforms.
Once the decision to add FR rainwear to the program is reached, thought must be given to which minimum performance standard the garments should meet. There are a couple of performance standards that are commonly referenced in the FR clothing market. Often, however, rainwear is labeled flame-resistant without referencing a performance standard at all or with reference to an irrelevant document.
The ASTM F2733 document is a performance standard for rainwear intended for protection against flame hazards including flash fire. ASTM F1891 is the counterpart performance standard for FR rainwear worn for protection against electric arc. Both standards define and require specialized tests to measure protective qualities of the materials when exposed to simulated flash fire and electric arc, respectively. Depending on the material, some rainwear can be dual-labeled to indicate that it meets the requirements of both standards. In addition, minimum performance requirements for FR rainwear against multiple tests including those measuring strength, waterproofness and vertical flammability are mandated by these standards.
Be warned, however, that it is common in our industry to see garments that are labeled flame-resistant because they have been tested against NFPA 701. This document does define a flammability test, but it is meant for curtains and draperies to be used in public places. This is not the proper standard of measure for wearers who could be exposed to flash fire or electric arc in the workplace.
Another common but misleading reference on labels of FR rainwear is ASTM D6413 which is a test method, not a performance standard. ASTM D6413 defines the procedure for conducting the vertical flame test but does not establish pass/fail criteria. There are no performance requirements associated with ASTM D6413.
Even when there are pass/fail criteria set for the vertical flame test, some materials popularly used in FR rainwear pass the test by melting and shrinking away from the flame thereby generating misleading results.
When specifying flame-resistant rainwear, consider the hazard that the wearer will face. If exposure to flash fire is possible, the pertinent performance standard is ASTM F2733. If exposure to electric arc is the hazard, specify rainwear that meets ASTM F1891.
